This invention relates to a carton blank feeder, and more particularly, to a carton blank feeder for a side seam gluer of the type that forms blanks into flat folded cartons and feeds them continuously to a cartoner.
The problem of feeding carton blanks is that the blanks, when stacked together, are quite heavy. The weight of the stack makes difficult the stripping off of blanks, one at a time, to feed them into a side seam gluer. Yet it is desirable to have a large stack so that an operator is not required to be in constant attendance continuously loading small groups of blanks into the magazine in order to keep the weight off the discharge end of the magazine. Compounding the problem is that the cut edges of the cartons tend to interlock, thereby adding to the difficulty of feeding blanks in a uniform manner.
One approach to a solution to the problem is shown in U.S. Pat. No. 4,093,207 assigned to the assignee of the present invention. In that patent, there is disclosed an upper magazine and a lower magazine or feed hopper. In the upper magazine, a large stack of blanks is supported on two spaced rollers at the lower discharge end of the upper magazine. The rollers rotate on demand from the lower stack and feed small groups of blanks onto the lower stack. A feeding mechanism is provided to remove the blanks one at a time from the lower stack. While this blank feeding mechanism has proved generally satisfactory, it, too, has a problem. The tendency of the blanks to interlock at their rough edges makes it difficult for the rollers at the lower end of the upper magazine to feed blanks in very small numbers to the lower stack. Sometimes a chunk of blanks that may be an inch thick will drop through. That chunk shakes the machine, and the somewhat sensitive feeder is caused to misfeed. If nothing else, misfeeding a blank disrupts the operation of the cartoner downstream from the side seam gluer.
In another type of feeder, a horizontal friction belt pulls blanks, one at a time, off the bottom of a stack and feeds them past a metering blade that permits only one blank to pass the blade. The need for the blanks to slide off the bottom of the stack requires preconditioning (fanning) of the blanks as they are added to the stack and constant operator attendance to more or less continuously "nudge" the stack to assure constant feeding.